Electrochromic privacy window

ABSTRACT

An electrochromic (EC) privacy window includes an EC pane unit including a first EC device having a bright state and a dark state, and a privacy device facing the EC pane unit and having a bright state and a privacy state configured to attenuate visible radiation transmitted through the window. In some embodiments, when the privacy device is in the privacy state, the window has transmitted haze of greater that 80%. In other embodiments, when the privacy device is in the privacy state and the first EC device is in the dark state, the window has a visible transmittance of about 0.1% or less.

FIELD

The present invention is generally directed to electrochromic (EC)windows configured to provide privacy through light modulation.

BACKGROUND OF THE INVENTION

Residential and commercial buildings represent a prime opportunity toimprove energy efficiency and sustainability in the United States. Thebuildings sector alone accounts for 40% of the United States' yearlyenergy consumption (40 quadrillion BTUs, or “quads”, out of 100 total),and 8% of the world's energy use. Lighting and thermal management eachrepresent about 30% of the energy used within a typical building, whichcorresponds to around twelve quads each of yearly energy consumption inthe US. Windows cover an estimated area of about 2,500 square km in theUS and are a critical component of building energy efficiency as theystrongly affect the amount of natural light and solar gain that enters abuilding. Recent progress has been made toward improving window energyefficiency through the use of inexpensive static coatings that eitherretain heat in cold climates (low emissive films) or reject solar heatgain in warm climates (near-infrared rejection films).

Currently, static window coatings can be manufactured at relatively lowcost. However, these window coatings are static and not well suited forlocations with varying climates. A window including an electrochromic(EC) device overcomes these limitations by enhancing window performancein all climates.

However, one of the shortcomings of conventional EC windows is theinability to achieve a sufficiently dark state to allow for use inprivacy applications. Accordingly, there is a need for smart windowssuitable for privacy applications.

SUMMARY

According to various embodiments, provided is an electrochromic (EC)window that includes an EC device and a privacy device.

According to various embodiments, an electrochromic (EC) privacy windowcomprises an EC pane unit comprising a first EC device having a brightstate and a dark state, and a privacy device facing the EC pane unit andhaving a bright state and a privacy state configured to attenuatevisible radiation transmitted through the window. In some embodiments,when the privacy device is in the privacy state the window hastransmitted haze of greater that 80%. In other embodiments, when theprivacy device is in the privacy state and the first EC device is in thedark state, the window has a visible transmittance of about 0.1% orless.

According to other embodiments, an electrochromic (EC) privacy windowcomprises an EC pane unit comprising a first EC device having a brightstate and a dark state, and a privacy device facing the EC pane unit andhaving a bright state and a privacy state configured to attenuatevisible radiation transmitted through the window, where the privacydevice comprises a switchable mirror device or film, a polymer-dispersedliquid crystal device or film, or a tunable liquid crystal filter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are schematic representations of EC devices according tovarious embodiments.

FIG. 2 is a schematic representation of an electrochromic device thatmay be tuned to produce a particular color, according to variousembodiments or the present disclosure.

FIGS. 3A to 3D are sectional views of a smart window, according tovarious embodiments of the present disclosure.

FIG. 4 is a sectional view of a smart window, according to variousembodiments of the present disclosure.

FIG. 5 is a sectional view of a smart window, according to variousembodiments of the present disclosure.

FIG. 6 is a sectional view of a smart window, according to variousembodiments of the present disclosure.

FIG. 7 is a sectional view of a smart window, according to variousembodiments of the present disclosure.

FIG. 8 is a sectional view of a smart window, according to variousembodiments of the present disclosure.

FIG. 9 is a sectional view of a smart window, according to variousembodiments of the present disclosure.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which exemplary embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the exemplaryembodiments set forth herein. Rather, these exemplary embodiments areprovided so that this disclosure is thorough, and will fully convey thescope of the invention to those skilled in the art. In the drawings, thesize and relative sizes of layers and regions may be exaggerated forclarity. Like reference numerals in the drawings denote like elements.

It will be understood that when an element or layer is referred to asbeing disposed “on” or “connected to” another element or layer, it canbe directly on or directly connected to the other element or layer, orintervening elements or layers may be present. In contrast, when anelement is referred to as being disposed “directly on” or “directlyconnected to” another element or layer, there are no interveningelements or layers present. It will be understood that for the purposesof this disclosure, “at least one of X, Y, and Z” can be construed as Xonly, Y only, Z only, or any combination of two or more items X, Y, andZ (e.g., XYZ, XYY, YZ, ZZ).

Various embodiments disclosed herein provide electrochromicnanostructured materials capable of selectively modulating radiation innear-infrared (NIR) and visible spectral regions. The material mayinclude nanostructured doped transition metal oxides with ternarycompounds of the type A_(x)M_(z)O_(y). In various embodimentA_(x)M_(z)O_(y) compounds, if it is assumed that z=1, then 0.08≤x≤0.5(preferably 0.25≤x≤0.35), and 2≤y≤3. In various embodiments, since thenanostructures may be non-uniform as a function of depth, x mayrepresent an average doping content. To operate, the subject materialmay be fabricated into an electrode that will change optical propertiesafter driven by an applied voltage.

In order to improve the performance of EC window coatings, selectivemodulation of NIR and visible spectra radiation, and avoidance ofdegrading effects of UV radiation, may be desired. Various embodimentsmay provide single-component electrochromic nanostructured materialscapable of selectively modulating NIR and visible spectral regions.Further, since certain spectral regions may damage the electrochromicnanostructured material, the various embodiments may incorporate atleast one protective material and/or protective layer to prevent suchdamage.

The various embodiments provide devices and methods for enhancingoptical changes in windows using electrochromic nanostructured materialsfabricated into an electrode to form an electrochromic device. Invarious embodiments, the material may undergo a reversible change inoptical properties when driven by an applied potential. Based on theapplied potential, the electrochromic nanostructured materials maymodulate NIR radiation (wavelength of around 780-2500 nm), as well asvisible radiation (wavelength of around 400-780 nm). In an example, thedevice may include a first nanostructured material that modulatesradiation in a portion of the NIR spectral region and in the visiblespectral region, and a second nanostructured material that modulatesradiation in an overlapping portion of the NIR spectral region such thatthe NIR radiation modulated by the device as a whole is enhanced andexpanded relative to that of just the first nanostructured material. Invarious embodiments, the material may operate in multiple selectivemodes based on the applied potential.

Further, the various embodiments may include at least one protectivematerial to prevent or reduce damage to an electrochromic nanostructuredmaterial that may result from repeated exposure to radiation in the UVspectral region. In an example, a protective material may be used toform at least one barrier layer in the device that is positioned toblock UV radiation from reaching the first nanostructured material andelectrolyte. In another example, a protective material may be used toform a layer that is positioned to block free electron or hole chargecarriers created in the electrolyte due to absorption of UV radiation bythe nanostructured electrode material from migrating to that material,while allowing conduction of ions from the electrolyte (i.e., anelectron barrier and ion conductor).

In various embodiments, control of individual operating modes formodulating absorption/transmittance of radiation in specific spectralregions may occur at different applied biases. Such control may provideusers with the capability to achieve thermal management within buildingsand other enclosures (e.g., vehicles, etc.), while still providingshading when desired.

FIGS. 1A-1C illustrate embodiment electrochromic devices. It should benoted that such electrochromic devices may be oriented upside down orsideways from the orientations illustrated in FIGS. 1A-1C. Furthermore,the thickness of the layers and/or size of the components of the devicesin FIGS. 1A-1C are not drawn to scale or in actual proportion to oneanother other, but rather are shown as representations.

In FIG. 1A, an embodiment electrochromic device 100 may include a firsttransparent conductor layer 102 a, a working electrode 104, a solidstate electrolyte 106, a counter electrode 108, and a second transparentconductor layer 102 b. Some embodiment electrochromic devices may alsoinclude one or more optically transparent support layers 110 a, 110 brespectively positioned in front of the first transparent conductorlayer 102 a and/or positioned behind the second transparent conductorlayer 102 b. The support layers 110 a, 110 b may be formed of atransparent material such as glass or plastic.

The first and second transparent conductor layers 102 a, 102 b may beformed from transparent conducting films fabricated using inorganicand/or organic materials. For example, the transparent conductor layers102 a, 102 b may include inorganic films of transparent conducting oxide(TCO) materials, such as indium tin oxide (ITO) or fluorine doped tinoxide (FTO). In other examples, organic films in transparent conductorlayers 102 a, 102 b may include graphene and/or various polymers.

In the various embodiments, the working electrode 104 may includenanostructures 112 of a doped or undoped transition metal oxide bronze,and optionally nanostructures 113 of a transparent conducting oxide(TCO) composition shown schematically as circles and hexagons forillustration purposes only. As discussed above, the thickness of thelayers of the device 100, including and the shape, size and scale ofnanostructures is not drawn to scale or in actual proportion to eachother, but is represented for clarity. In the various embodiments,nanostructures 112, 113 may be embedded in an optically transparentmatrix material or provided as a packed or loose layer of nanostructuresexposed to the electrolyte.

In the various embodiments, the doped transition metal oxide bronze ofnanostructures 112 may be a ternary composition of the type AxMzOy,where M represents a transition metal ion species in at least onetransition metal oxide, and A represents at least one dopant. Transitionmetal oxides that may be used in the various embodiments include, butare not limited to any transition metal oxide which can be reduced andhas multiple oxidation states, such as niobium oxide, tungsten oxide,molybdenum oxide, vanadium oxide, titanium oxide and mixtures of two ormore thereof. In one example, the nanostructured transition metal oxidebronze may include a plurality of undoped tungsten oxide (WO_(3-x))nanoparticles, where 0≤x≤0.33, such as 0≤x≤0.1.

In various embodiments, the at least one dopant species may be a firstdopant species that, upon application of a particular first voltagerange, causes a first optical response. The applied voltage may be, forexample, a negative bias voltage. Specifically, the first dopant speciesmay cause a surface plasmon resonance effect on the transition metaloxide by creating a significant population of delocalized electroniccarriers. Such surface plasmon resonance may cause absorption of NIRradiation at wavelengths of around 780-2000 nm, with a peak absorbanceat around 1200 nm. In various embodiments, the specific absorbances atdifferent wavelengths may be varied/adjusted based other factors (e.g.,nanostructure shape, size, etc.), discussed in further detail below. Inthe various embodiments, the first dopant species may be an ion speciesselected from the group of cesium, rubidium, and lanthanides (e.g.,cerium, lanthanum, praseodymium, neodymium, promethium, samarium,europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium,ytterbium, and lutetium).

In various embodiments, the dopant may include a second dopant speciesthat causes a second optical response based upon application of avoltage within a different, second particular range. The applied voltagemay be, for example, a negative bias voltage. In an embodiment, thesecond dopant species may migrate between the solid state electrolyte106 and the nanostructured transition metal oxide bronze of the workingelectrode 104 as a result of the applied voltage. Specifically, theapplication of voltage within the particular range may cause the seconddopant species to intercalate and deintercalate the transition metaloxide structure. In this manner, the second dopant may cause a change inthe oxidation state of the transition metal oxide, which may cause apolaron effect and a shift in the lattice structure of the transitionmetal oxide. This shift may cause absorption of visible radiation, forexample, at wavelengths of around 400-780 nm.

In various embodiments, the second dopant species may be anintercalation ion species selected from the group of lanthanides (e.g.,cerium, lanthanum, praseodymium, neodymium, promethium, samarium,europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium,ytterbium, and lutetium), alkali metals (e.g., lithium, sodium,potassium, rubidium, and cesium), and alkali earth metals (e.g.,beryllium, magnesium, calcium, strontium, and barium). In otherembodiments, the second dopant species may include a charged protonspecies.

In various embodiments, nanostructures 113 may optionally be mixed withthe doped transition metal oxide bronze nanostructures 112 in theworking electrode 104. In the various embodiments, the nanostructures113 may include at least one TCO composition, which prevents UVradiation from reaching the electrolyte and generating electrons. In anexample embodiment, the nanostructures 113 may include an indium tinoxide (ITO) composition, which may be a solid solution of around 60-95wt % (e.g., 85-90 wt %) indium(III) oxide (In₂O₃) and around 5-40 wt %(e.g., 10-15 wt %) tin(IV) oxide (SnO₂). In another example embodiment,the nanostructures 113 may include an aluminum-doped zinc oxide (AZO)composition, which may be a solid solution of around 99 wt % zinc oxide(ZnO) and around 2 wt % aluminum(III) oxide (Al₂O₃). Additional oralternative TCO compositions that may be used to form nanostructures 113in the various embodiments include, but are not limited to, indiumoxide, zinc oxide and other doped zinc oxides such as gallium-doped zincoxide and indium-doped zinc oxide.

The TCO composition of nanostructures 113 may be transparent to visiblelight/radiation and, upon application of the first voltage, may modulateabsorption of NIR radiation at wavelengths of around 1200-2500 nm, withpeak absorbance around 2000 nm (e.g., at a longer peak wavelength thanthe bronze nanoparticles 112, but with overlapping absorption bands). Inparticular, application of the first voltage may cause an increase infree electron charge carriers, and therefore cause a surface plasmonresonance effect in at least one TCO composition of nanostructures 113.In an embodiment in which the TCO composition is ITO, the surfaceplasmon resonance effect may be caused by oscillation of free electronsproduced by the replacement of indium ions (In³⁺) with tin ions (Sn⁴⁺).Similar to the transition metal oxide bronze, such surface plasmonresonance may cause a change in absorption properties of the TCOmaterial. In some embodiments, the change in absorption properties maybe an increase in absorbance of NIR radiation at wavelengths thatoverlaps with that of the nanostructures 112. Therefore, the addition ofTCO composition nanostructures 113 to the working electrode 104 mayserve to expand the range of NIR radiation absorbed (e.g., atwavelengths of around 780-2500 nm) compared to that of thenanostructures 112 alone (e.g., at wavelengths of around 780-2000 nm),and to enhance absorption of some of that NIR radiation (e.g., atwavelengths of around 1200-2000 nm).

Based on these optical effects, the nanostructure 112 and optionalnanostructure 113 of the working electrode may progressively modulatetransmittance of NIR and visible radiation as a function of appliedvoltage by operating in at least three different modes. For example, afirst mode may be a highly solar transparent (“bright”) mode in whichthe working electrode 104 is transparent to NIR radiation and visiblelight radiation. A second mode may be a selective-IR blocking (“cool”)mode in which the working electrode 104 is transparent to visible lightradiation but absorbs NIR radiation. A third mode may be a visibleblocking (“dark”) mode in which the working electrode 104 absorbsradiation in the visible spectral region and at least a portion of theNIR spectral region. In an example, application of a first voltagehaving a negative bias may cause the electrochromic device to operate inthe cool mode, blocking transmittance of NIR radiation at wavelengths ofaround 780-2500 nm. In another example, application of a second negativebias voltage having a higher absolute value than the first voltage maycause the electrochromic device to operate in the dark state, blockingtransmittance of visible radiation (e.g., at wavelengths of around400-780 nm) and NIR radiation at wavelengths of around 780-1200 nm. Inanother example, application of a third voltage having a positive biasmay cause the electrochromic device to operate in the bright state,allowing transmittance of radiation in both the visible and NIR spectralregions. In various embodiments, the applied voltage may be between −5Vand 5V, preferably between −2V and 2V. For example, the first voltagemay be −0.25V to −0.75V, and the second voltage may be −1V to −2V. Inanother example, the absorbance of radiation at a wavelength of 800-1500nm by the electrochromic device may be at least 50% greater than itsabsorbance of radiation at a wavelength of 450-600 nm.

Alternatively, the nanostructure 112 and optional nanostructure 113 ofthe working electrode may modulate transmittance of NIR and visibleradiation as a function of applied voltage by operating in two differentmodes. For example, a first mode may be a highly solar transparent(“bright”) mode in which the working electrode 104 is transparent to NIRradiation and visible light radiation. A second mode may be a visibleblocking (“dark”) mode in which the working electrode 104 absorbsradiation in the visible spectral region and at least a portion of theNIR spectral region. In an example, application of a first voltagehaving a negative bias may cause the electrochromic device to operate inthe dark mode, blocking transmittance of visible and NIR radiation atwavelengths of around 780-2500 nm. In another example, application of asecond voltage having a positive bias may cause the electrochromicdevice to operate in the bright mode, allowing transmittance ofradiation in both the visible and NIR spectral regions. In variousembodiments, the applied voltage may be between −2V and 2V. For example,the first voltage may be −2V, and the second voltage may be 2V.

In various embodiments, the solid state electrolyte 106 may include atleast a polymer material and a plasticizer material, such thatelectrolyte may permeate into crevices between the transition metaloxide bronze nanoparticles 112 (and/or nanoparticles 113 if present).The term “solid state,” as used herein with respect to the electrolyte106, refers to a polymer-gel and/or any other non-liquid material. Insome embodiments, the solid state electrolyte 106 may further include asalt containing, for example, an ion species selected from the group oflanthanides (e.g., cerium, lanthanum, praseodymium, neodymium,promethium, samarium, europium, gadolinium, terbium, dysprosium,holmium, erbium, thulium, ytterbium, and lutetium), alkali metals (e.g.,lithium, sodium, potassium, rubidium, and cesium), and alkali earthmetals (e.g., beryllium, magnesium, calcium, strontium, and barium). Inan example embodiment, such salt in the solid state electrolyte 106 maycontain a lithium and/or sodium ions. In some embodiments, the solidstate electrolyte 106 may initially contain a solvent, such as butanol,which may be evaporated off once the electrochromic device is assembled.In some embodiments, the solid state electrolyte 106 may be around 40-60wt % plasticizer material, preferably around 50-55 wt % plasticizermaterial. In an embodiment, the plasticizer material may include atleast one of tetraglyme and an alkyl hydroperoxide. In an embodiment,the polymer material of the solid state electrolyte 106 may bepolyvinylbutyral (PVB), and the salt may be lithiumbis(trifluoromethane). In other embodiments, the solid state electrolyte106 may include at least one of lithium phosphorus oxynitride (LiPON)and tantalum pentoxide (Ta₂O₅).

In some embodiments, the electrolyte 106 may include a sacrificial redoxagent (SRA). Suitable classes of SRAs may include, but are not limitedto, alcohols, nitrogen heterocycles, alkenes, and functionalizedhydrobenzenes. Specific examples of suitable SRAs may include benzylalcohol, 4-methylbenzyl alcohol, 4-methoxybenzyl alcohol, dimethylbenzylalcohol (3,5-dimethylbenzyl alcohol, 2,4-dimethylbenzyl alcohol etc.),other substituted benzyl alcohols, indoline,1,2,3,4-tetrahydrocarbazole, N,N-dimethylaniline, 2,5-dihydroanisole,etc. In various embodiments, the SRA molecules may create an air stablelayer that does not require an inert environment to maintain charge.

Polymers that may be part of the electrolyte 106 may include, but arenot limited to, poly(methyl methacrylate) (PMMA), poly(vinylbutyral-co-vinyl alcohol-co-vinyl acetate) (PVB), poly(ethylene oxide)(PEO), fluorinated co-polymers such as poly(vinylidenefluoride-co-hexafluoropropylene), poly(acrylonitrile) (PAN), poly(vinylalcohol) (PVA), etc. Plasticizers that may be part of the polymerelectrolyte formulation include, but are not limited to, glymes(tetraglyme, triglyme, diglyme etc.), propylene carbonate, ethylenecarbonate, ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate,1-butyl-3-methylimidazolium hexafluorophosphate,1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl) imide,1-butyl-1-methyl-pyrrolidinium bis(trifluoromethane sulfonyl)imide,etc.), N,N-dimethylacetamide, and mixtures thereof.

In some embodiments, the electrolyte 106 may include, by weight, 10-30%polymer, 40-80% plasticizer, 5-25% lithium salt, and 0.5-10% SRA.

The counter electrode 108 of the various embodiments should be capableof storing enough charge to sufficiently balance the charge needed tocause visible tinting to the nanostructured transition metal oxidebronze in the working electrode 104. In various embodiments, the counterelectrode 108 may be formed as a conventional, single component film, ananostructured film, or a nanocomposite layer.

In some embodiments, the counter electrode 108 may be formed from atleast one passive material that is optically transparent to both visibleand NIR radiation during the applied biases. Examples of such passivecounter electrode materials may include CeO₂, CeVO₂, TiO₂, indium tinoxide, indium oxide, tin oxide, manganese or antimony doped tin oxide,aluminum doped zinc oxide, zinc oxide, gallium zinc oxide, indiumgallium zinc oxide, molybdenum doped indium oxide, Fe₂O₃, and/or V₂O₅.In other embodiments the counter electrode 108 may be formed from atleast one complementary material, which may be transparent to NIRradiation but which may be oxidized in response to application of abias, thereby causing absorption of visible light radiation. Examples ofsuch complementary counter electrode materials may include Cr₂O3, MnO₂,FeO₂, CoO₂, NiO₂, RhO₂, or IrO₂. The counter electrode materials mayinclude a mixture of one or more passive materials and/or one or morecomplementary materials described above.

Without being bound to any particular theory, it is believed that theapplication of a first voltage in the various embodiments may cause theinterstitial dopant species (e.g., cesium) in the crystal structure ofthe transition metal oxide bronze to have a greater amount of freecarrier electrons and/or to cause the interstitial dopant species (e.g.,lithium ions from the electrolyte) to perform non-faradaic capacitive orpseudo-capacitive charge transfer on the surface of the nanostructures112, which may cause the surface plasmon resonance effect to increasethe absorption of NIR radiation. In this manner, the absorptionproperties of the transition metal oxide bronze characteristics maychange (i.e., increased absorption of NIR radiation) upon application ofthe first voltage. Further, application of a second voltage having ahigher absolute value than the first voltage in the various embodimentsmay cause faradaic intercalation of an intercalation dopant species(e.g., lithium ions) from the electrolyte into the transition metaloxide nanostructures. It is believed that the interaction of this dopantspecies provides interstitial dopant atoms in the lattice which createsa polaron effect. In this manner, the lattice structure of transitionmetal oxide nanoparticles may experience a polaron-type shift, therebyaltering its absorption characteristics (i.e., shift to visibleradiation) to block both visible and near infrared radiation.

In some embodiments, in response to radiation of certain spectralregions, such as UV (e.g., at wavelengths of around 10-400 nm) may causeexcitons to be generated in the polymer material of the solid stateelectrolyte 106. The UV radiation may also excite electrons in the dopedtransition metal oxide bronze to move into the conduction band, leavingholes in the valence band. The generated excitons in the polymermaterial may dissociate to free carriers, the electrons of which may beattracted to the holes in the valence band in the doped transition metaloxide bronze (e.g., cesium-doped tungsten trioxide (Cs_(x)WO₃)) ofnanoparticles 112. Since electrochemical reduction of various transitionmetal oxide bronzes by such free electron charge carriers may degradetheir performance (i.e., from unwanted coloration of the transitionmetal oxide bronze), embodiment devices may include one or more layer ofa protective material to prevent UV radiation from reaching the solidstate electrolyte 106, in addition to or instead of nanostructures 113mixed into the working electrode.

FIG. 1B illustrates an embodiment electrochromic device 150 thataddresses degradation of the doped transition metal oxide bronzenanostructures 112. Similar to device 100 shown in FIG. 1A, device 150may include a first transparent conductor layer 102 a, a workingelectrode 104, a solid state electrolyte 106, a counter electrode 108, asecond transparent conductor layer 102 b, and one or more opticallytransparent support layers 110 a, 110 b. In addition, device 150 mayinclude one or more protective layers 116 a, 116 b made of a materialthat absorbs UV radiation. In an example embodiment, the device 150 mayinclude a first protective layer 116 a disposed between a first supportlayer 110 a and the first transparent conductor layer 102 a. The devicemay optionally include a second protective layer 116 b disposed betweena second support layer 110 b and the second transparent conductor layer102 b. Alternatively, the UV protective layer 116 a may be disposed onthe exterior surface of the first support layer 110 a, or may bedisposed between the first transparent conductor 102 a and the workingelectrode 104. In other words, the first and/or second UV protectivelayers 116 a, 116 b may be disposed between any of the layers of theelectrochromic device 150, such that UV radiation is substantiallyprevented from reaching the working electrode 104.

The UV radiation absorbing material of the one or more protective layers116 a, 116 b of the various embodiments may be any of a number ofbarrier films. For example, the one or more protective layers 116 a, 116b may be a thin film of at least one TCO material, which may include asame as or different from TCO compositions in the nanostructures 113. Inan example embodiment, a protective layer 116 a of the device 150 may bean ITO thin film, and therefore capable of absorbing UV radiation byband-to-band absorption (i.e., absorption of a UV photon providingenough energy to excite an electron from the valence band to theconduction band). In another example embodiment, the device may includethe TCO nanostructures 113 made of ITO, as well as a protective layer116 a composed of an ITO thin film. Alternatively, the TCOnanostructures 113 may form a separate thin film layer 116 b disposedbetween the transition metal oxide bronze nanoparticles 112 and thetransparent conductor 102 a. In some embodiments, the UV radiationabsorbing materials of protective layers 116 a, 116 b may includeorganic or inorganic laminates.

In another embodiment, at least one UV protective layer, such asprotective layer 116 a in FIG. 1B, may be a UV radiation reflector madeof a high index transparent metal oxide. Since birds can see radiationin the UV range, a UV reflector may be implemented in embodimentspositioned as outside windows in order to prevent birds from hitting thewindows. In some other embodiments, UV radiation absorbing organicmolecules and/or inorganic UV radiation absorbing nanoparticles (e.g.,zinc oxide, indium oxide, ITO, etc.) may be incorporated within theelectrolyte 106 material.

FIG. 1C illustrates another embodiment electrochromic device 170 thataddresses degradation of the doped transition metal oxide bronzenanostructures 112 by controlling the effects of the electron chargecarriers generated in the electrolyte from exposure to UV radiation.Similar to devices 100 and 150 discussed above with respect to FIGS. 1Aand 1B respectively, device 170 may include a first transparentconductor layer 102 a, a working electrode 104, a solid stateelectrolyte 106, a counter electrode 108, a second transparent conductorlayer 102 b, and one or more optically transparent support layers 110 a,110 b. In addition, device 170 may include a protective layer 118positioned between the working electrode 104 and the electrolyte 106.The protective layer 118 may be composed of one or more ionicallyconductive and electrically insulating material.

As discussed above, without being bound to any particular theory, it isbelieved that the migration of intercalation ions between theelectrolyte 106 and the working electrode 104 is responsible for atleast some of the device's capability to modulate spectral absorption.Therefore, in order to maintain operability of the device, theelectrically insulating material used to form the protective layer 118should also be ionically conductive. That is, the material of theprotective layer 118 may prevent or reduce free electrons in the solidstate electrolyte layer 106 from reducing the transition oxide bronze ofnanoparticles 112, while allowing the diffusion of ions of anintercalation dopant species (e.g., Na, Li, etc.) between theelectrolyte 106 and working electrode 104. In an example embodiment, theelectrically insulating material that makes up the protective layer 118may be tantalum oxide, such as tantalum pentoxide (Ta₂O₅), which blocksmigration of electrons from the electrolyte 106 while allowing diffusionof the intercalation dopant species ions (e.g., lithium ions) from theelectrolyte 106. In this manner, degradation of the transition metaloxide bronze is reduced or prevented by controlling the effect of theabsorbed UV radiation in addition to or instead of instead of blockingits absorption. Other example materials that may be used to form theprotective layer 118 in addition to or instead of tantalum pentoxide mayinclude, without limitation, strontium titanate (SrTiO₃), zirconiumdioxide (ZrO₂), indium oxide, zinc oxide, tantalum carbide, niobiumoxide, and various other dielectric ceramics having similar electricaland/or crystalline properties to tantalum pentoxide.

In an alternative embodiment, instead of or in addition to theprotective layer 118, the nanostructures 112 may each be encapsulated ina shell containing an electrically insulating and ionically conductivematerial, which may be the same as or different from the material of theprotective layer 118 (e.g., tantalum oxide, strontium titanate, zincoxide, indium oxide, zirconium oxide, tantalum carbide, or niobiumoxide).

In an example embodiment, each nanostructure 112 may have a core ofcubic or hexagonal unit cell lattice structure tungsten bronze,surrounded by a shell of tantalum pentoxide.

In some embodiments, the electrolyte 106 may include a polymer thatreduces damage to the device due to UV radiation. The polymer may be anyof a number of polymers that are stable upon absorption of UV radiation(e.g., no creation of proton/electron pairs). Examples of such polymersmay include, but are not limited to, fluorinated polymers withouthydroxyl (—OH) groups (e.g., polyvinylidene difluoride (PVDF)).

In another embodiment, a positive bias may be applied to the counterelectrode 108 to draw UV radiation generated electrons from theelectrolyte 106 to the counter electrode 108 in order to reduce orprevent electrons from the electrolyte 106 from moving to the workingelectrode 104 to avoid the free electron-caused coloration of the dopedtransition metal oxide bronze in the working electrode 104.

In another embodiment, a device may include more than one of, such asany two of, any three of, or all four of: (i) a protective layer ofelectrically insulating material (e.g., protective layer 118 orprotective material shells around the bronze nanoparticles), (ii) one ormore protective layer of UV radiation absorbing material (e.g.,protective layer(s) 116 a and/or 116 b in FIG. 1B and/or UV radiationabsorbing organic molecules and/or inorganic UV radiation absorbingnanoparticles incorporated within the electrolyte 106 material), (iii)electrolyte polymer that is stable upon absorption of UV radiation,and/or (iv) application of positive bias to the counter electrode 108.In various embodiments, the nanostructures 113 may be included in oromitted from electrochromic devices 150, 170.

In another embodiment, the protective layer(s) 116 a and/or 116 b maycomprise a stack of metal oxide layers. Alternatively, the stack maycomprise a separate component that is provided instead of or in additionto the layer(s) 116 a and/or 116 b. The stack may provide improvement inthe reflected color of the electrochromic device. Prior art devicesgenerally have a reddish/purplish color when viewed in reflection. Thestack may comprise index-matched layers between the glass andtransparent conductive oxide layer to avoid the reddish/purplishreflected color. As noted above, the index-matched layer can serve asthe UV absorber or be used in addition to another UV absorber. The stackmay comprise a zinc oxide based layer (e.g., ZnO or AZO) beneath anindium oxide based layer (e.g., indium oxide or ITO).

Compared to nanocomposite electrochromic films, the various embodimentsmay involve similar production by utilizing a single nanostructuredmaterial in the working electrode to achieve the desired spectralabsorption control in both NIR and visible regions, and anothernanostructured material to enhance and expand such control in the NIRregion. Further, the various embodiments may provide one or moreadditional layer(s) of a protective material to minimize degradation ofthe single nanostructured material.

In some embodiments, the working electrode and/or the counter electrodemay additionally include at least one material, such as an amorphousnano structured material, that enhances spectral absorption in the lowerwavelength range of the visible region. In some embodiments, the atleast one amorphous nanostructured material may be at least onenanostructured amorphous transition metal oxide.

In particular, the amorphous nano structured materials may provide colorbalancing to the visible light absorption that may occur due to thepolaron-type shift in the spectral absorption of the doped-transitionmetal oxide bronze. As discussed above, upon application of the secondvoltage having a higher absolute value, the transition metal oxidebronze may block (i.e., absorb) radiation in the visible range. Invarious embodiments, the absorbed visible radiation may have wavelengthsin the upper visible wavelength range (e.g., 500-700 nm), which maycause the darkened layer to appear blue/violet corresponding to theun-absorbed lower visible wavelength range (e.g., around 400-500 nm). Invarious embodiments, upon application of the second voltage, the atleast one nanostructured amorphous transition metal oxide may absorbcomplementary visible radiation in the lower visible wavelength range(e.g., 400-500 nm), thereby providing a more even and complete darkeningacross the visible spectrum with application of the second voltage. Thatis, use of the amorphous nanostructured material may cause the darkenedlayer to appear black.

In some embodiments, at least one nanostructured amorphous transitionmetal oxide may be included in the working electrode 104 in addition tothe doped-transition metal oxide bronze nanostructures 112 and theoptional TCO nanostructures 113. An example of such material in theworking electrode 104 may be, but is not limited to, nanostructuredamorphous niobium oxide, such as niobium(II) monoxide (NbO) or otherniobium oxide materials (e.g., NbO_(x)). In some embodiments, thecounter electrode 108 may include, as a complementary material, at leastone nanostructured amorphous transition metal oxide. That is, inaddition to optically passive materials, the counter electrode 108 mayinclude at least one material for color balancing (i.e., complementing)the visible radiation absorbed in the working electrode (i.e., by thetransition metal oxide bronze. An example of such material in thecounter electrode 108 may be, but is not limited to, nanostructuredamorphous nickel oxide, such as nickel(II) oxide (NiO) or other nickeloxide materials (e.g., NiO_(x)).

In the various embodiments, nanostructures that form the working and/orcounter electrode, including the at least one amorphous nanostructuredmaterial, may be mixed together in a single layer. An example of a mixedlayer is shown in FIG. 1A with respect to transition metal oxide bronzenanostructures 112 and TCO nanostructures 113. Alternatively, nanostructures that form the working and/or counter electrode, including theat least one amorphous nanostructured material, may be separatelylayered according to composition. For example, a working electrode mayinclude a layer of amorphous NbO_(x) nanostructures, a layer oftransition metal oxide bronze nanostructures, and a layer of ITOnanostructures, in any of a number of orders.

The nanostructured transition metal oxide bronzes that may be part ofthe working electrode 104 in various embodiment devices can be formedusing any of a number of low cost solution process methodologies. Forexample, solutions of Nb:TiO₂ and Cs_(x)WO₃ may be synthesized usingcolloidal techniques. Compared to other synthetic methodologies,colloidal synthesis may offer a large amount of control over thenanostructure size, shape, and composition of the nanostructuredtransition metal oxide bronze. After deposition, a nanostructuredtransition metal oxide bronze material in the working electrode 104 maybe subjected to a thermal post treatment in air to remove and capligands on the surface of the nanostructures.

In various embodiments, nanostructured amorphous transition metal oxidematerials may be formed at room temperature from an emulsion and anethoxide precursor. For example, procedures used to synthesize tantalumoxide nanoparticles that are described in “Large-scale synthesis ofbioinert tantalum oxide nanoparticles for X-ray computed tomographyimaging and bimodal image-guided sentinel lymph node mapping” by M H Ohet al. (J Am Chem Soc. 2011 Apr. 13; 133(14):5508-15), incorporated byreference herein, may be similarly used to synthesize amorphoustransition metal oxide nanoparticles. For example, an overall syntheticprocess of creating the nanoparticle, as described in Oh et al., mayadopted from the microemulsion synthesis of silica nanoparticles. Insuch process, a mixture of cyclohexane, ethanol, surfactant, and acatalysis for the sol-gel reaction may be emulsified. The ethoxideprecursor may be added to the emulsion, and uniform nanoparticles may beformed by a controlled-sol gel reaction in the reverse micelles at roomtemperature within around 5 minutes. The sol-gel reaction may becatalyzed, for example, by NaOH.

In some embodiments, the nanostructured amorphous transition metal oxidemay be sintered at a temperature of at least 400° C. for at least 30minutes, such as 400 to 600° C. for 30 to 120 minutes to form a porousweb. In an example embodiment, the porous web may be included in aworking electrode 104, with the tungsten bronze nanoparticles and ITOnanoparticles incorporated in/on the web. Alternatively, the sinteringstep may be omitted and the nano structured amorphous transition metaloxide may remain in the device in the form of nanoparticles havingamorphous structure. In this embodiment, the device containing thenanostructured amorphous transition metal oxide may include or may omitthe protective layer(s) 116 a, 116 b, and 118, the UV stable electrolytepolymer, and the application of positive bias to the counter electrode.

Electrochromic responses of prepared nano structured transition metaloxide bronze materials (e.g., Cs_(x)WO₃, Nb:TiO₂, etc.) may bedemonstrated by spectro-electrochemical measurements.

In various embodiments, the shape, size, and doping levels ofnanostructured transition metal oxide bronzes may be tuned to furthercontribute to the spectral response by the device. For instance, the useof rod versus spherical nanostructures 112 may provide a wider level ofporosity, which may enhance the switching kinetics. Further, a differentrange of dynamic plasmonic control may occur for nanostructures withmultiple facets, such as at least 20 facets.

Various embodiments may also involve alternation of the nanostructures112 that form the working electrode 104. For example, the nanostructuresmay be nanoparticles of various shapes, sizes and/or othercharacteristics that may influence the absorption of NIR and/or visiblelight radiation. In some embodiments, the nanostructures 112 may beisohedrons that have multiple facets, preferably at least 20 facets.

In some embodiments, the transition metal oxide bronze nanostructures112 may be a combination of nanoparticles having a cubic unit cellcrystal lattice (“cubic nanoparticles”) and nanoparticles having ahexagonal unit cell crystal lattice (“hexagonal nanoparticles”). Eachunit cell type nanoparticle contributes to the performance of theworking electrode 104. For example, the working electrode 104 mayinclude both cubic and hexagonal cesium doped tungsten oxide bronzenanoparticles. In alternative embodiments, the working electrode 104 mayinclude either cubic or hexagonal cesium doped tungsten oxidenanoparticles. For example, the working electrode 104 may include cubiccesium-doped tungsten oxide (e.g. Cs₁W₂O_(6-X)) nanoparticles andamorphous niobium oxide nanoparticles or hexagonal cesium-doped tungstenoxide (e.g. Cs_(0.29)W₁O₃) nanoparticles without niobium oxide. Inalternative embodiments, the working electrode 104 may include undopedtungsten oxide (e.g. WO_(3-x)) nanoparticles where 0≤x≤0.33, such as0<x≤0.17, including 0<x≤0.1.

For example, upon application of the first (i.e., lower absolute value)voltage described above, the hexagonal bronze nanostructures 112 mayblock NIR radiation having wavelengths in the range of around 800-1700nm, with the peak absorption at the mid-NIR wavelength of around 1100nm. The cubic bronze nanostructures 112 may block NIR radiation havingwavelengths in the close-NIR range with the peak absorption of around890 nm. The indium oxide based (including ITO) and/or zinc oxide based(including AZO) nanostructures 113 may be included in the workingelectrode 104 to block the higher wavelength IR radiation uponapplication of the first voltage. Thus, the cubic bronze and hexagonalbronze nanostructures may block respective close and mid-NIR radiation(e.g., using the Plasmon effect), while the nanostructures 113 may blockthe higher wavelength IR radiation.

Upon application of the second (i.e., higher absolute value) voltagedescribed above, the cubic bronze nanostructures 112 may block visibleand NIR radiation having wavelengths in the range of around 500-1500 nm,with the peak absorption at the close-NIR wavelength of around 890 nm(e.g., using the polaron effect). Optionally, the amorphous niobiumoxide may also be added to the working electrode 104 to block the shortwavelength visible radiation (e.g., 400 to 500 nm wavelength).

The cubic bronze nanostructures block visible radiation via the polaroneffect at a lower applied voltage than the hexagonal bronzenanostructures. Thus, the second voltage may have an absolute valuewhich is below the value at which the hexagonal bronze nano structuresblock visible radiation via the polaron effect such that thesenanostructures do not contribute to blocking of visible radiation.Alternatively, the second voltage may have an absolute value which isabove the value at which the hexagonal bronze nanostructures blockvisible radiation via the polaron effect such that these nanostructuresalso contribute to blocking of visible radiation.

Embodiment nanoparticles that form the working electrode 104 may bearound 4-6 nm in diameter, and may include 40 to 70 wt %, such as around50 wt % cubic tungsten bronze nanostructures, 15 to 35 wt %, such asaround 25 wt % hexagonal tungsten bronze nanostructures, and optionally15 to 35 wt %, such as around 25 wt % ITO nanostructures. In someembodiments, in order to achieve color balancing as described above, thenanoparticles that form the working electrode 104 may optionally includearound 5-10 wt % amorphous NbO_(x) nanostructures in place of cubictungsten bronze nanostructures. In this embodiment, the devicecontaining two types of bronze nanoparticles may include or may omit theprotective layer(s) 116 a, 116 b, and 118, the UV stable electrolytepolymer, the application of positive bias to the counter electrode, andthe amorphous niobium oxide.

In summary, the working electrode 104 may include one or more of thefollowing components:

-   -   (a) metal oxide bronze nanostructures 112 having (i) a        cubic, (ii) hexagonal, or (iii) a combination of cubic and        hexagonal unit cell lattice structure;    -   (b) protective (i) indium oxide based (including ITO) and/or        zinc oxide based (including AZO) nanostructures 113;    -   (c) amorphous niobium oxide nanoparticles and/or web; and/or    -   (d) additional nanostructures selected from undoped tungsten        oxide, molybdenum oxide, titanium oxide, and/or vanadium oxide.

The counter electrode 108 may include one or more of the followingcomponents:

-   -   (a) passive electrode material selected from cerium(IV) oxide        (CeO₂), titanium dioxide (TiO₂), cerium(III) vanadate (CeVO₂),        indium(III) oxide (In₂O₃), tin-doped indium oxide, tin(II) oxide        (SnO₂), manganese-doped tin oxide, antimony-doped tin oxide,        zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), iron(III)        oxide (Fe₂O₃), and vanadium(V) oxide (V₂O₅);    -   (b) an active electrode material selected from chromium(III)        oxide (Cr₂O₃), manganese dioxide (MnO₂), iron(II) oxide (FeO),        cobalt oxide (CoO), nickel(II) oxide (NiO), rhodium(IV) oxide        (RhO₂), and iridium(IV) oxide (IrO₂);    -   (c) amorphous nickel oxide nanoparticles and/or web; and/or    -   (d) conductivity enhancer nanoparticles selected from indium        oxide, ITO, and zinc oxide.

While the various embodiments are described with respect toelectrochromic windows, the embodiment methods, systems, and devices mayalso be used in materials for other types of smart windows. Such smartwindows may include, but are not limited to, polymer-dispersed liquidcrystals (PLDD), liquid crystal displays (LCDs), thermochromics, etc.

Color Tunability

Color tunability of electrochromic devices is applicable to a variety ofapplications. According to various embodiments, the present disclosureprovides electrochromic devices having the capability of achieving amultitude of colors that may not currently be available in the market.The technique for achieving color tunability in one embodiment is basedon the selection of the composition and the deposition of the activematerials. While colored glass may be achieved by the use of doped glass(e.g., glass with metal impurities added to impart color), this is anon-standard product from most primary glass manufacturers on theirfloat lines, and this entails cost premium. By contrast, the presentlydisclosed color tunability can be achieved in a nearly cost-neutralfashion, as the nanostructures can be synthesized for approximately thesame cost for devices of different colors.

According to various embodiments, the present disclosure allows color ofelectrochromic devices to be tuned by utilizing various nanostructurecompositions, or mixtures thereof, in the active, i.e. working,electrode of an electrochromic device. In particular, depending on thenanostructure components used and/or a ratio therebetween, a wide rangeof colors may be achieved, such as, for example, gray, blue, green,purple, and brown, but the present disclosure is not limited thereto.For example, an electrochromic device may include a working electrodeincluding a variety of metal oxide nanostructures, such as nanocrystalsand amorphous metal oxide nanoparticles. Such nanostructures may includeWO₃, Cs_(x)WO₃ (where 0.2≤x≤0.4, e.g., 0.29≤x≤0.31), Cs₁WO_(6-σ) (where0≤σ≤0.3), NbO_(x), TiO₂, MoO₃, NiO₂, V₂O₅, or combinations thereof.

FIG. 2 is a schematic representation of an electrochromic device 180that may be configured to produce a particular color, according tovarious embodiments or the present disclosure. The electrochromic device180 is similar to the electrochromic device 150 of FIG. 1B, so only thedifferences therebetween will be discussed in detail.

Referring to FIG. 2, the electrochromic device 180 includes a workingelectrode 104. In particular, the working electrode 104 may includevarious nanostructures as discussed above, in order to producecorresponding colors. For example, the working electrode may includefirst nanostructures 115 and/or second nanostructures 117, according toa particular color the working electrode 104 is configured to form. Inother words, the second nanostructures 117 may be omitted, or additionalnanostructures may be added.

For example, in order to produce a blue color, the working electrode 104may include about 100 wt. % of WO₃ as the first nanostructures 115 andmay omit the second nanostructures 117. In order to produce a greencolor, the working electrode 104 may include about 60 wt. % ofCs_(x)WO₃, such as Cs_(0.29)WO₃, hexagonal crystal lattice structurenanocrystals as the first nanostructures 115, and about 40 wt. % ofindium tin oxide (e.g., Sn:In₂O₃) nanocrystals as the secondnanostructures 117.

In order to produce a brown color, the working electrode 104 may includeabout 100 wt. % NbO_(x) nanoparticles (e.g., Nb₂O_(5-σ) where 0≤σ≤0.1)as the first nanostructures 115 and may omit the second nanostructures117. In order to produce a purple color, the working electrode 104 mayinclude about 100 wt. % Nb:TiO₂ nanocrystals as the first nanostructures115 and may omit the second nanostructures 117.

According to various embodiments, the present inventors discovered thatelectrochromic devices that produce a neutral gray color may beunexpectedly advantageous. In particular, since the human eye is lesssensitive with respect to detecting variations in neutral gray colors,as compared to variations in other colors, color variations in adjacentelectrochromic devices that produce neutral gray colors are lessnoticeable to the human eye. As such, tone variations between adjacentelectrochromic devices producing a neutral gray color may be greaterthan for other colors, without being noticeable to the human eye.

For example, in order to produce a neutral gray color, the firstnanostructures 115 may include amorphous niobium oxide (“NbO_(x)”)nanoparticles (e.g., Nb₂O_(5-σ) where 0≤σ≤0.1), and the secondnanostructures 117 may include cesium doped tungsten oxide (“CWO”)nanoparticles having a cubic crystal lattice structure (e.g.,CsW₂O_(6-σ) nanocrystals, where 0≤σ≤0.3). Herein, the CWO nanoparticlesmay be referred to as “nanocrystals”, due to their crystallinestructure. The relative amounts of the NbO_(x) nanoparticles and CWOnanocrystals included in the working electrode 104 may result invariations in the color of the working electrode 104.

In particular, the working electrode 104 may include a nanostructuredlayer comprising from about 40 to about 80 wt. % of the NbO_(x)nanoparticles and from about 60 to about 10 wt. % of the CWOnanocrystals. In other embodiments, the working electrode 104 mayinclude from about 65 to about 80 wt. % of the NbO_(x) nanoparticles andfrom about 35 to about 20 wt. % of the CWO nanocrystals. In someembodiments, the working electrode may include from about 40 to 50 wt. %of the NbO_(x) nanoparticles and from about 60 to about 50 wt. % of theCWO nanocrystals.

According to various embodiments, the NbO_(x) nanoparticles may have anaverage particle size of from about 2 to about 6 nm, such as from about3 to about 5 nm. For example, the NbO_(x) nanoparticles may have anaverage particle size of about 4 nm. The CWO nanocrystals may have anaverage particle size of from about 3 to about 7 nm, such as from about4 to about 6 nm. For example, the CWO nanocrystals may have an averageparticle size of about 5 nm.

According to other embodiments, the working electrode 104 may include ananostructured layer comprising a mixture of amorphous molybdenum oxidenanoparticles (“MoO₃”) and tungsten oxide nanocrystals (“WO₃”), in orderto produce a neutral gray color. In particular, the working electrode104 may include a nanostructured layer comprising from about 40 to about80 wt. % of the MoO₃ nanoparticles and from about 60 to about 10 wt. %of the WO₃ nanocrystals. In other embodiments, the working electrode 104may include from about 65 to about 80 wt. % of the MoO₃ nanoparticlesand from about 35 to about 20 wt. % of the WO₃ nanocrystals. In someembodiments, the working electrode may include from about 40 to 50 wt. %of the MoO₃ nanoparticles and from about 60 to about 50 wt. % of the WO₃nanocrystals.

According to some embodiments, the working electrode 104 may include ananostructured layer comprising molybdenum doped tungsten oxidenanocrystals. For example, the molybdenum doped tungsten oxidenanocrystals may be represented by the general formula Mo_(x)WO₃ (where0.1≤x≤0.75, e.g., 0.2≤x≤0.5).

According to various embodiments, the working electrode 104 may includea nanostructured layer comprising a mixture of amorphous niobium oxide(e.g., NbO_(x) described above) nanoparticles and undoped tungsten oxidenanocrystals, in order to produce a neutral gray color. In someembodiments, when the tungsten oxide is initially manufactured, thetungsten oxide may be dark blue in color. This may indicate oxygenvacancies in the tungsten oxide, meaning that the tungsten oxide isoxygen deficient (i.e., non-stoichiometric). The tungsten oxide may beannealed in air after initial manufacturing (e.g., before or after beingplaced into the electrochromic device), which may result in the tungstenoxide becoming transparent. The air-annealing may result in the fillingof oxygen deficiencies in the tungsten oxide nanocrystals, which mayresult in the tungsten oxide being stoichiometric or lessnon-stoichiometric.

For example, the tungsten oxide may be represented by WO_(3-x), where0≤x≤0.33, such as 0≤x≤0.17. The tungsten oxide may be oxygen deficient,such that 0<x≤0.33, such as 0<x≤0.17. The tungsten oxide (e.g., undopedtungsten oxide) may have a cubic crystal structure. In particular, theworking electrode 104 may include from about 85 to about 95 wt. %NbO_(x) nanoparticles and from about 15 to about 5 wt. % WO_(3-x)nanocrystals. In other embodiments, the working electrode 104 mayinclude from about 88 to about 93 wt. % NbO_(x) nanoparticles and fromabout 13 to about 7 wt. % WO_(3-x) nanocrystals. In other embodiments,the working electrode 104 may include about 90 wt. % NbO_(x)nanoparticles and about 10 wt. % WO_(3-x) nanocrystals.

In some embodiments, the working electrode 104 may have a thicknessranging from about 1200 to about 1800 nm. For example, the workingelectrode 104 may have a thickness ranging from about 1300 to about 1700nm, or a thickness ranging from about 1400 to about 1600 nm. In otherembodiments, the working electrode 104 may have a thickness of about1500 nm and may include about 90 wt. % NbO_(x) nanoparticles and about10 wt. % oxygen deficient WO_(3-x) nanocrystals.

In various embodiments, the working electrode 104 comprises from about40 to about 95 wt. % of amorphous niobium oxide nanoparticles and fromabout 60 to about 5 wt. % of cesium doped tungsten oxide nanoparticleshaving a cubic crystal lattice structure, or undoped, oxygen deficienttungsten oxide, based on the total weight of the nano structures.

EC Privacy Windows

Privacy applications are especially important for various EC windowapplications, such as residential window applications, for example. Toinsure privacy, an EC privacy window should have a dark state visibleradiation transmission amount of about 0.1% or less, such as 0.01 to0.1%, or an optical density of about 3.0 or more, such as 3.0 to 5.0.However, conventional EC devices generally have a dark state visibleradiation transmittance of about 3-5%.

In order to provide privacy without providing such low levels of visibleradiation transmittance, an EC privacy window may be configured toscatter light transmitted there through or thereto. In particular, suchan EC window should have a degree of scattering, as measured by atransmitted haze, of about 80% or more, such as 80% to 99%.

According to various embodiments, EC windows that are configured forprivacy applications are provided. In particular, provided are ECwindows that include a light control layer or device (e.g., privacydevice) in addition to an EC device. For example, as discussed below,various embodiments provide EC windows that include a second EC device,a polymer-dispersed liquid crystal (PDLC) layer, a switchable mirror,and/or a liquid crystal (LC) layer that behaves like a notch filterhaving a high optical density in a wavelength range of interest.

FIG. 3A is a top schematic view of an EC privacy window 300 (e.g.,insulated glass unit, (IGU)), according to various embodiments of thepresent disclosure. Referring to FIG. 3A, the window 300 includes an ECpane unit 302, a sealing separator 310, a first pane 312, a privacydevice 340, a control unit 350, and optionally a low emissivity (Low-E)coating 330. The EC pane unit 302 and the first pane 312 may beseparated by a void or space 306. Herein, a “pane” refers to asubstantially transparent substrate, such as a glass or plasticsubstrate.

EC privacy windows components may be referred to as having “inner” and“outer” surfaces. Herein, the “inner” surfaces face the space 306, andthe “outer” surfaces face away from the space 306 toward the interior ofa structure, such as a building or vehicle. As shown in FIG. 3A, aprivacy window may be depicted as having a particular orientation withrespect to an external environment (outdoor environment depicted by thesun) and an internal environment (indoor environment of the structure).Thus, the EC pane unit 302 faces the Sun and the first pane 312 facesthe interior of the structure. However, the orientation of an EC privacywindow may be reversed in some embodiments, such that the EC pane unit302 faces the interior of the structure and the first pane 312 faces theSun.

The sealing separator 310 extends along the perimeter of the window 300and may be configured to hermetically seal a space 306 between the ECpane unit 302 and the first pane 312. The space 306 may be charged withan inert gas such as argon or nitrogen. In one embodiment, the space 306is substantially liquid free. In one embodiment the space 306 is chargedwith an inert gas and is substantially liquid (e.g., moisture) free. Inone embodiment, the space 306 has a moisture content of less than about<0.1 ppm.

The Low-E coating 330 may be configured to minimize the amount ofultraviolet and infrared light that can pass through the EC window 300,without substantially compromising the amount of visible radiation thatis transmitted there through. In FIG. 3A, the Low-E coating 330 isdisposed on an inner surface of the EC pane unit 302. However, the Low-Ecoating 330 may be disposed on an outer of the EC pane unit 302, or maybe disposed on inner or outer surfaces of the first pane 312. In someembodiments, one or more panes of the EC pane unit 302, may be formed ofLow-E glass, and/or the first pane 312 may be formed of Low-E glass, andthe Low-E coating 330 may be omitted.

The EC pane unit 302 may include a third pane 316, a fourth pane 318,and an EC device 320 disposed there between. The EC device 320 mayinclude the transparent conductors, counter electrodes, electrolytes,insulating materials, working electrodes, and/or Bragg reflectors asdescribed above with regard to FIGS. 1A-2C.

The EC device 320 may be any of the EC devices 100, 150, 170, 180described above, for example. The EC device 320 may have a dark statevisible radiation transmittance ranging from about 3% to about 7%, suchas from about 4% to about 6%, or about 5%. The EC device 320 may have abright state visible radiation transmittance ranging from about 60% toabout 70%, such as from about 63% to about 67%, or about 65%. In variousembodiments, the EC device 320 may have a neutral gray color.

The privacy device 340 may be disposed on an inner surface of the firstpane 312, as shown in FIG. 3A. However, the present disclosure is notlimited to such a location. For example, the privacy device may bedisposed on inner or outer surfaces of the first pane 312 or the ECdevice 320, as shown in FIGS. 3B-3D, for example.

The privacy device 340 may be configured to actively or passivelymodulate light transmitted thereto, such as light received from theexternal environment through the EC device 320. In particular, theprivacy device may absorb, reflect, filter, and/or scatter lighttransmitted thereto. For example, the privacy device 340 may include aliquid crystal (LC) device, a tunable filter LC device, a reflective LCdevice, a polymer-dispersed liquid crystal (PDLC) device, an EC device,a transition metal switchable mirror (TMSM) device, a one-way mirror, orthe like.

In some embodiments, the privacy device 340 may be configured such that,when used alone or in conjunction with the EC device 320, the window 300has an optical density of greater than about 3.0, and/or a visibleradiation transparency of about 0.1% or less, in a privacy state. Inother embodiments, the privacy device 340 may be configured such that,when used alone or in conjunction with the EC device 320, the window 300has a transmitted haze of greater than 80%, in a privacy state. Herein,a “privacy state” refers to when at least a privacy device of an ECprivacy window is in a dark state.

The control unit 350 may be configured to control the operation of theEC device 320 and/or the privacy device 340.

FIG. 3B is a top schematic view of an EC privacy window 301, accordingto various embodiments of the present disclosure. The window 301 issimilar to the window 300, so only the differences therebetween will bediscussed in detail.

Referring to FIG. 3B, the privacy device 340 may be disposed on an innersurface of the EC pane unit 302. The Low-E coating 330 may be disposedon an inner surface of the first pane 312.

FIG. 3C is a top schematic view of an EC privacy window 303, accordingto various embodiments of the present disclosure. The window 303 issimilar to the window 301, so only the differences therebetween will bediscussed in detail.

Referring to FIG. 3C, the privacy device 340 may be disposed on an innersurface of the first pane 312. The Low-E coating 330 may be disposed onan outer surface of the first pane 312.

FIG. 3D is a top schematic view of an EC privacy window 305, accordingto various embodiments of the present disclosure. The window 305 issimilar to the window 303, so only the differences therebetween will bediscussed in detail.

Referring to FIG. 3D, the privacy device 340 may be disposed on an outersurface of the first pane 312. The Low-E coating 330 may be disposed onan inner surface of the first pane 312. In addition, the window 305 mayoptionally include a second pane 314 disposed on an outer surface of thefirst pane 312, with the privacy device 340 being disposed therebetween.

FIG. 4 is a top schematic view of an EC privacy window 400, according tovarious embodiments of the present disclosure. The window 400 is similarto the window 300, so only the differences therebetween will bediscussed in detail.

Referring to FIG. 4, the window 400 includes a first EC pane unit 302,an opposing second EC pane unit 304, a sealing separator 310, andoptionally a Low-E coating 330. The second EC pane unit 304 includes afirst pane 312, a second pane 314, and a privacy device 440 disposedtherebetween. The privacy device 440 may be an EC device that includesmultiples layered elements, such as the transparent conductors, counterelectrodes, electrolytes, insulating materials, working electrodes,and/or Bragg reflectors described above with regard to FIGS. 1A-2.

The sealing separator 310 is disposed about peripheral regions of thefirst and second EC pane units 302, 304, without substantially obscuringa viewable region of the window 400. The sealing separator 310 may beconfigured to hermetically seal a space or chamber 306 that is at leastpartially defined by opposing surfaces of the EC pane units 302, 304.The space 306 may be charged with an inert gas such as argon ornitrogen. In one embodiment, the space 306 is substantially liquid free.In one embodiment the space 306 is charged with an inert gas and issubstantially liquid (e.g., moisture) free. In one embodiment, the space306 has a moisture content of less than about <0.1 ppm.

The Low-E coating 330 may be configured to minimize the amount ofultraviolet and infrared light that can pass through the EC window 400,without compromising the amount of visible radiation that is transmittedthere through. In FIG. 3, the Low-E coating 330 is disposed on anexterior surface (e.g., a surface facing the outdoor environment) of thesecond EC pane unit 304. However, the Low-E coating 330 may be disposedon interior or exterior surfaces of either of the EC pane units 302,304. In some embodiments, one or more panes of the EC pane units 302,304 may be formed of Low-E glass and the Low-E coating 330 may beomitted.

In some embodiments, one or both of the EC pane units 302, 304 mayinclude any of the EC devices described above. In various embodiments,at least one of the EC pane units 302, 304 may have a neutral graycolor. Herein, “visible transmittance” refers to an amount of visibleradiation is transmitted through an element, with 0% visibletransmittance referring to no visible light transmission, and with 100%visible light transmittance referring to complete or nearly completetransparency.

For example, the EC pane units 302, 304 may each have a dark statevisible transmittance of about 3% or less, such as about 2.9%, or about2.8% and may each have a bright state visible transmittance ranging fromabout 60% to about 70%, such as from about 63% to about 67%, or about65%. Herein, the dark state of the second EC pane unit 304 may also bereferred to as a privacy state. In addition, the window 400 may bereferred to as having a bright state, where both the EC pane units 302,304 are in the bright state, and a privacy or dark state, where both theEC pane units 302, 304 are in the dark or privacy state.

Accordingly, when the first EC pane unit 302 is in the dark state, andthe second EC unit 304 is in the privacy/dark state, the window mayassume a privacy state. In the privacy state, the window 400 may have avisible transmittance of about 0.1% or less, such as 0.09% or 0.08% orless, e.g., 0.05 to 0.09%. The inclusion of two EC pane units may alsoprovide for improved sound isolation characteristics, as measured by asound transfer coefficient.

In other embodiments, the EC pane units 302, 304 may have differentvisible transmittance values. For example, the first EC pane unit 302may include a general EC device, and the second EC pane unit 304 may bea low-transmittance EC device.

In particular, the first EC pane unit 302 may have a dark state visibletransmittance ranging from about 3% to about 7%, such as from about 4%to about 6%, or about 5%, and may have bright state visibletransmittance ranging from about 60% to about 70%, such as from about63% to about 67%, or about 65%.

The second EC pane unit 304 may have a dark/privacy state visibletransmittance of ranging from about 0.5% to about 3%, such as from about0.75% to about 2%, or about 1%, and may have a bright state visibletransmittance ranging from about 35% to about 45%, such as from about37% to about 43%, or about 40%. As such, the window 400 may have a totaldark or privacy state visible transmittance of about 0.05% and a brightstate visible transmittance of about 26%.

FIG. 5 is a sectional view of an EC privacy window 500, according tovarious embodiments of the present disclosure. The window 500 is similarto the window 400, so only the differences therebetween will bediscussed in detail.

Referring to FIG. 5, the window 500 includes an EC pane unit 302, asealing separator 310, a privacy device 540, a first pane 312, anopposing second pane 314, and an optional Low-E coating 330. The privacydevice 540 is disposed between the first and second panes 312, 314. Assuch, the privacy device 540 may have improved structural stability,physical protection, and/or environmental protection, as compared to aprivacy device that is adhered to a single pane.

The privacy device 540 may include first and second electrodes 546A,546B respectively disposed on opposing surfaces of the first and secondpanes 312, 314, and an active region 542 disposed between the first andsecond electrodes 546A, 546B. The first and second electrodes 546A, 546Bmay be connected to a voltage source. The privacy device 540 may beconfigured to absorb, reflect, filter, and/or scatter light transmittedthereto, such as visible radiation.

In some embodiments, the privacy device 540 may be configured such that,when used in conjunction with the EC pane unit 302, the window 500 hasan optical density of greater than about 3.0, and/or a visibletransmittance of about 0.1% or less, in a privacy state. In otherembodiments, the privacy device 540 may be configured such that, whenused in conjunction with the EC pane unit 302, the window 500 has atransmitted haze of greater than 80% in a privacy state.

In some embodiments, the active region 542 may include apolymer-dispersed liquid crystal (PDLC) layer. The PDLC layer may beformed by dissolving or dispersing liquid crystals into a liquidpolymer, followed by solidification or curing of the polymer. During thechange of the polymer from a liquid to solid, the liquid crystals maybecome incompatible with the solid polymer and may form dropletsthroughout the solid polymer. The curing conditions affect the size ofthe droplets, which affects the final optical properties of the PDLClayer. The electrodes 546A, 546B may be formed of transparent,conductive materials, as described above with regard to transparentelectrodes of the EC devices.

When no voltage is applied to the electrodes 546A, 546B, the PDLC layerassumes a translucent privacy state (e.g., dark state), where the liquidcrystals are randomly arranged in the droplets. This results inscattering of light as it passes through the window 500, producing ahazy “milky white” appearance. When a voltage is applied to theelectrodes 546A, 546B, the PDLC layer assumes a transparent state, wherethe electric field formed between the electrodes 546A, 546B causes theliquid crystals to align, allowing light to pass through the dropletswith very little scattering. The degree of transparency (e.g., hazeamount) can be controlled by the magnitude of the applied voltage.

In other embodiments, the active region 542 may include a liquid crystallayer configured to operate as a tunable notch filter with high opticaldensity in a wavelength range of interest. The liquid crystal layer maybe tuned according to a voltage applied to the electrodes 546A, 546B.For example, the liquid crystal layer may be tuned to absorb visibleradiation, and/or other wavelength ranges such as NIR radiation. Theliquid crystal layer may have a dark state visible transmittance, thatranges from about 0.005% to about 1%, such as from about 0.05% to about0.5%, or about 0.1%, and may have a bright state visible transmittanceranging from about 75% to about 85%, such as from about 77% to about83%, or about 80%. For example, the tunable liquid crystal filter 542has optical transmittance of about 0.1% over a wavelength range of fromabout 650 nm to about 890 nm.

In other embodiments, the active region 542 may include a reflectiveliquid crystal layer. For example, the privacy device 540 may include aswitchable mirror, such as an e-TransFlector™ switchable mirroravailable from Kent Optronics, Inc, which switches between reflectiveand transmissive (i.e., bright) states. As such, the privacy device 540may have a reflective (i.e., “dark”) state visible transmittance ofabout 0.1% and a bright state visible transmittance of between about 40and 87%. In this case, when the privacy device 540 and the EC pane unit302 are operated concurrently, the window 500 may have a dark statevisible transmittance of about 0.005% and a bright state visibletransmittance of about 59%.

FIG. 6 is a sectional view of an EC privacy window 600, according tovarious embodiments of the present disclosure. The window 600 is similarto the window 500, so only the differences therebetween will bedescribed in detail.

Referring to FIG. 6, the window 600 includes a first pane 312, a secondpane 314, and a privacy device 640 disposed therebetween. The privacydevice 640 may include a first transparent electrode 646A, a secondtransparent electrode 646B, a mirror electrode 648, and an electrolytelayer 650.

The privacy device 640 may operate as a transition-metal switchablemirror (TMSM). The mirror electrode 648 may include magnesium and one ormore transition metals, such as titanium and/or nickel. The electrolytelayer 650 may include ionic species, such as lithium ions. The mirrorelectrode 648 may be converted from a transparent to a reflecting stateand back again, by application of current or voltage to the electrodes646A, 646B, which causes the migration of ions from the electrolytelayer 650 into the mirror electrode 648. As a result, the reflectivityof the mirror electrode 648 may be controlled according to the appliedvoltage.

In a bright (i.e., transmissive) state, the TMSM privacy device 640 mayhave a visible radiation transparency of about 50% and reflectivity ofabout 10%. In a reflective (i.e., “dark”) state, the TMSM privacy device640 may have a visible radiation transparency of about 0.5% andreflectivity of about 75%.

The EC pane unit 302 and the TMSM privacy device 640 may be operatedindependently or concurrently. The window 600 may have a total visibleradiation transmittance ranging from about 0.005% (dark state) to about59% (bright state).

In one embodiment, the privacy devices 340, 440, 540 and/or 640 may beoperated independently of the EC device in the EC pane unit 302. In oneembodiment, the window is configured to operate in the following threestates: (i) a bright state where the EC device is in the bright stateand the privacy device is in the bright state; (ii) a dark state wherethe EC device is in the dark state and the privacy device is in thebright state; and (iii) a privacy state where the privacy device is inthe privacy state and the first EC device is in the dark state.

In another embodiment, the EC window is configured to operate in thefollowing four states: (1) a bright state where the EC device is in thebright state and the privacy device is in the bright state; (2) a darkstate where the EC device is in the dark state and the privacy device isin the bright state; (3) a bright privacy state where the privacy deviceis in the privacy state and the EC device is in the bright state; and(4) a dark privacy state where the privacy device is in the privacystate the EC device is in the dark state. For example, when the ECdevice is in the dark state, the visible transmittance of the window maybe reduced from about 2% to about 0.1% or less, such as about 0.01%, byswitching the privacy device from the bright state to the privacy state.

In various embodiments, the EC window may be configured to operate inmore than four states. For example, in addition to the above fourstates, the EC window may include a number of intermediate statesbetween the bright state and the dark privacy state. In particular, theEC device and/or the privacy device may be configured to have multipledifferent levels of visible transmittance and/or haze. For example, theEC device may have multiple intermediate states between bright and darkstates, and the privacy device may have a bright state and a privacystate. In an embodiment, the control unit may also be configured tocontrol the EC device to be in a plurality of additional intermediatestates between the bright state and the dark state such that the windowis further configured to operate in a plurality of additionalintermediate states between the bright state and the dark privacy state.The control unit may control the EC device to be in the plurality ofadditional intermediate states by applying intermediate values ofcontrol voltage or current to the EC device.

For example, the EC device may have intermediate states that have avisible transmittance of one or more of 5%, 10%, 20%, 30%, 40%, 50%,60%, 70%, and/or 80%, etc. When the privacy device is configured to bein the bright state, then the EC window may have intermediate stateshaving visible transmittance of one or more of 5%, 10%, 20%, 30%, 40%,50%, 60%, 70%, and/or 80%, etc.

FIG. 7 is a top schematic view of an EC privacy window 700, according tovarious embodiments of the present disclosure. Referring to FIG. 7, thewindow 700 includes a first pane 702, a first EC device 704, and asecond EC device 706. Each EC device 704, 706 may include a firstelectrode 710, a second electrode 714, and an electrolyte layer 712disposed therebetween. Herein, either of the EC devices 704, 706 maybereferred to, or operate as, a privacy device. The first and secondelectrodes 710, 714 may be different ones of a working electrode and acounter electrode. For example, the second electrodes 714 may be workingelectrodes, and the first electrodes 710 may be counter electrodes.

The window 700 may also include a second pane 720 and a third pane 722.The second pane 720 may be configured to protect the second EC device706, and the third pane 722 may be configured to protect the first ECdevice 704. The first pane 702 is located between the second and thirdpanes 720, 730 and may separate the first and second EC devices 704, 706from each other. Although not shown, the window 700 may include asealing frame.

FIG. 8 is a top schematic view of an EC privacy window 800, according tovarious embodiments of the present disclosure. Referring to FIG. 8, thewindow 800 may be a triple glazed window including, an EC pane unit 810,a LC pane unit 820 (e.g., privacy device), and a first pane 802 disposedtherebetween. The window 800 may also include a sealing separator 804configured to support the EC pane unit 810, the first pane 802, and theLC pane unit 820, such that a space 806 is formed between the EC paneunit 810 and the first pane 802, and a space 806 is formed between thefirst pane 802 and the LC pane unit 820. The spaces 806 may be chargedwith air or an inert gas, such as argon or nitrogen.

The EC pane unit 810 may include a second pane 812, a third pane 814,and an EC device 816 disposed therebetween. The LC pane unit 820 mayinclude a fourth pane 822, a fifth pane 824, and a LC device 826disposed therebetween. The EC pane unit 810 may form an exterior surfaceof the window 800, and the LC pane unit 820 may form an interior surfaceof the window 800, according to various embodiments, since the EC paneunit is less sensitive to cold than the LC pane unit. Locating the LCpane unit 820 on the interior side of the window 800 may beneficiallyprotect the LC device 826 from temperature extremes, such as coldtemperatures that may negatively affect the performance of the EC device826. The LC pane unit 820 typically has a faster switching time than theEC pane unit 810 to quickly set the privacy state by blocking visiblelight. In contrast, the EC pane unit 810 typically blocks heat (i.e.,infrared radiation) and UV radiation. Thus, the EC and LC pane unitslocated in series in the EC window are capable of fast privacy stateswitching as well as blocking heat and UV radiation.

The window 800 may also include a Low-E layer or coating 830 disposed onthe first pane 802. While shown on the exterior surface of the firstpane 802, the Low-E coating 830 may be disposed on the interior surfacethereof, in some embodiments. In other embodiments, the first pane 802may be a double or triple silver pane, such as a SuperNeutral 68 panefrom Guardian Inc.

FIG. 9 is a top schematic view of an EC privacy window 801, according tovarious embodiments of the present disclosure. The window 801 is similarto the window 800, so only the difference therebetween will be discussedin detail.

Referring to FIG. 9, the window 801 is configured such that the firstpane 802 forms the interior surface of the window 801, the EC pane unit810 forms the exterior surface of the window 801, and the LC pane unit820 is disposed therebetween. The Low-E coating 830 may be disposed onthe exterior surface of the first pane 802.

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed, andmodifications and variations are possible in light of the aboveteachings or may be acquired from practice of the invention. Thedescription was chosen in order to explain the principles of theinvention and its practical application. It is intended that the scopeof the invention be defined by the claims appended hereto, and theirequivalents.

The invention claimed is:
 1. An electrochromic (EC) privacy windowcomprising: an EC pane unit comprising a first EC device having a brightstate and a dark state; and a privacy device facing the EC pane unit andhaving a bright state and a privacy state configured to attenuatevisible radiation transmitted through the window; wherein the first ECdevice comprises a working electrode having a neutral gray color; andwherein: when the privacy device is in the privacy state, the window hastransmitted haze of greater that 80%; or when the privacy device is inthe privacy state and the first EC device is in the dark state, thewindow has a visible transmittance of about 0.1% or less.
 2. The windowof claim 1, wherein: the privacy device-comprises a second EC devicehaving a bright state and a dark state corresponding to the privacystate; and the first and second EC devices each have a dark statevisible transmittance of about 3% or less.
 3. The window of claim 1,wherein: the privacy device comprises a second EC pane unit having abright state and a dark state corresponding to the privacy state, thedark state having visible transmittance of about 1% or less; and thefirst EC pane unit has a dark state visible transmittance of about 5% orless.
 4. The window of claim 3, further comprising a third pane locatedbetween the first EC pane unit and the second EC pane unit.
 5. Thewindow of claim 1, wherein the privacy device comprises apolymer-dispersed liquid crystal (PDLC) device or film having privacystate a visible transmittance of about 0.1% or less.
 6. The window ofclaim 1, wherein the privacy device comprises a tunable liquid crystalfilter device or film having a privacy state visible transmittance ofabout 0.1% or less.
 7. The window of claim 6, wherein the tunable liquidcrystal filter has an optical transmittance of about 0.1% over awavelength range of from about 650 nm to about 890 nm.
 8. The window ofclaim 1, wherein the privacy device comprises a transition metalswitchable mirror device or film having a privacy state visibletransmittance of about 1% or less.
 9. The window of claim 1, wherein theprivacy device comprises a reflective liquid crystal device having aprivacy state visible transmittance of about 1% or less.
 10. The windowof claim 1, further comprising: a first pane facing the EC pane unit;and a sealing separator configured to seal a space between the EC paneunit and the first pane.
 11. The window of claim 10, wherein the privacydevice is disposed on a surface of first EC device that faces the space,or wherein the privacy device is disposed on a surface of the first panethat faces the space.
 12. The window of claim 10, further comprising: asecond pane disposed on the first pane; and a low-emissivity coatingdisposed on the first pane or the EC pane unit; wherein the privacydevice is disposed between the first and second panes.
 13. The window ofclaim 1, wherein: when the privacy device is in the privacy state andthe first EC device is in the dark state, the window has a visibletransmittance of about 0.05% or less; and when the privacy device andthe EC device are in the bright state, the window has a visibletransmittance of at least about 26%.
 14. The window of claim 13, whereinthe privacy device comprises an electrochromic device or film, atransition metal switchable mirror device or film, or apolymer-dispersed liquid crystal device or film.
 15. The window of claim1, wherein: when the privacy device is in the privacy state and thefirst EC device is in the dark state, the window has a visibletransmittance of about 0.05% or less; and when the privacy device andthe EC device are in the bright state, the window has a visibletransmittance of at least about 52%.
 16. The window of claim 15, whereinthe privacy device comprises a tunable liquid crystal filter device orfilm.
 17. The window of claim 1, wherein the working electrode of thefirst EC device comprises: amorphous Nb₂O_(5-σ) nanoparticles, where0≤σ≤0.1, and CsW₂O_(6-σ) nanocrystals, where 0≤σ≤0.3; amorphous MoO₃nanoparticles and WO_(3-x), nanocrystals where 0≤x≤0.33; or Mo_(x)WO₃nanocrystals, where 0.1≤x≤0.75.
 18. The window of claim 1, furthercomprising a control unit configured to control the first EC device andthe privacy device, such that the window is configured to operate in: abright state where the first EC device is in the bright state and theprivacy device is in the bright state; a dark state where the first ECdevice is in the dark state and the privacy device is in the brightstate; and a privacy state where the privacy device is in the privacystate the first EC device is in the bright state.
 19. The window ofclaim 1, further comprising a control unit configured to control thefirst EC device and the privacy device, such that the window isconfigured to operate in: a bright state where the first EC device is inthe bright state and the privacy device is in the bright state; a darkstate where the first EC device is in the dark state and the privacydevice is in the bright state; and a privacy state where the privacydevice is in the privacy state and the first EC device is in the darkstate.
 20. The window of claim 1, further comprising a control unitconfigured to control the first EC device and the privacy device, suchthat the window is configured to operate in: a bright state where thefirst EC device is in the bright state and the privacy device is in thebright state; a dark state where the first EC device is in the darkstate and the privacy device is in the bright state; a first privacystate where the privacy device is in the privacy state and the first ECdevice is in the bright state; and a second privacy state where theprivacy device is in the privacy state and the first EC device is in thedark state.
 21. The window of claim 1, wherein: when the privacy deviceis in the privacy state, the window has transmitted haze of greater that80%; and when the privacy device is in the privacy state, and the firstEC device is in the dark state, the window has a visible transmittanceof about 0.1% or less.
 22. The window of claim 21, wherein the controlunit is further configured to control the first EC device to be in aplurality of additional intermediate states between the bright state andthe dark state such that the window is further configured to operate ina plurality of additional intermediate states between the bright stateand the second privacy state.
 23. An electrochromic (EC) privacy windowcomprising: an EC pane unit comprising a first EC device having a brightstate and a dark state; and a privacy device facing the EC pane unit andhaving a bright state and a privacy state configured to attenuatevisible radiation transmitted through the window, wherein the privacydevice comprises a switchable mirror device or film, a polymer-dispersedliquid crystal device or film, or a tunable liquid crystal filter, andwherein the first EC device comprises a working electrode having aneutral gray color and comprising: amorphous Nb₂O_(5-σ) nanoparticles,where 0≤σ≤0.1; and CsW₂O_(6-σ) nanocrystals, where 0≤σ≤0.3; amorphousMoO₃ nanoparticles and WO_(3-x), nanocrystals where 0≤x≤0.33; orMo_(x)WO₃ nanocrystals, where 0.1≤x≤0.75.
 24. The window of claim 23,wherein the privacy device comprises the switchable mirror device orfilm.
 25. The window of claim 24, wherein the switchable mirror deviceor film comprises a reflective liquid crystal device or a transitionmetal switchable mirror device.
 26. The window of claim 23, wherein theprivacy device comprises the polymer-dispersed liquid crystal device orfilm.
 27. The window of claim 23, wherein the privacy device comprisesthe tunable liquid crystal filter.
 28. The window of claim 23, wherein:when the privacy device is in the privacy state, the window has atransmitted haze of greater that 80%, and when the privacy device is inthe privacy state and the first EC device is in the dark state, thewindow has a visible transmittance of about 0.1% or less.
 29. The windowof claim 23, further comprising a control unit configured to control thefirst EC device and the privacy device, such that the window isconfigured to operate in: a bright state where the first EC device is inthe bright state and the privacy device is in the bright state; a darkstate where the first EC device is in the dark state and the privacydevice is in the bright state; a first privacy state where the privacydevice is in the privacy state and the first EC device is in the brightstate; and a second privacy state where the privacy device is in theprivacy state and the first EC device is in the dark state.
 30. Thewindow of claim 29, wherein the control unit configured to control thefirst EC device to be in a plurality of additional intermediate statesbetween the bright state and the dark state such that the window isfurther configured to operate in a plurality of additional intermediatestates between the bright state and the second privacy state.
 31. Thewindow of claim 23, further comprising: a first pane disposed between ECpane unit and the privacy device; and a sealing separator configured toseal a space between the EC pane unit and the first pane, and to seal aspace between the privacy device and the first pane.
 32. The window ofclaim 23, further comprising: a first pane facing the privacy device;and a sealing separator configured to seal a space between the EC paneunit and the privacy device, and to seal a space between the privacydevice and the first pane.